Proposed text for xyzValidIntervals/xyzInvalidIntervals

["C. M. Heard/VVNET, Inc." <[e-mail]>]

On Fri, 05 Jun 1998 Kaj Tesink wrote:
[ ... ]
> i attach a version [of PerfHist-TC-MIB] that i was working on;
> obviously this version needs work given the
> recent debate and some minor comments i received.
>
> i'll be off-line until july 5
> i'm making the bold request here for some text that would
> resolve the debate?

This note is an attempt to answer that request.  Since Kaj's post
went only to the atommib list and not the trunk-mib list, I am going
to reference all proposed text to the drafts that are currently
available in the ftp://ftp.ietf.org/internet-drafts directory, viz:

    draft-ietf-atommib-perfhistTC-01.txt
    draft-ietf-atommib-sonetng-02.txt
    draft-ietf-trunkmib-ds1-mib-08.txt
    draft-ietf-trunkmib-ds3-mib-08.txt

The "recent debate" to which Kaj refers is the discussion that has
taken place on the atommib and trunk-mib lists in the past two weeks
concerning the description of xyzValidIntervals and xyzInvalidIntervals.
It is obvious that the text that is presently in the above-mentioned
drafts confuses some of us and is in need of editorial clarification.
Some of you would like to see deeper changes than that, but let me
remind you what Jeff Johnson pointed out on 03 Jun 1998:

> Keep in mind that the origin of the Perf Hist TC MIB is the three trunk
> mibs (SONET, DS1, and DS3).  These definitions were factored out since they
> were common to all three mibs, and so that others could use them as well.
> I would love to make changes to the valid/invalid stuff, but it is
> impossible to do so without affecting implementations of the trunk mibs.

For this reason -- and avoid delaying the three trunk mibs any more than
the minimum necessary -- I wish to propose _nothing more_ than editorial
clarifications to the description clauses for these for these objects.

Also, this note addresses _only_ the xyzValidIntervals and
xyzInvalidIntervals objects.  I will address problems in the
descriptions of the xyzValidData objects in a subsequent memo.

Here is my list of the ambiguities, along with proposed fixes.

1.)  (From Jeff Johnson):  it is not clear from the description of
xyzInvalidIntervals that the value of xyzInvalidIntervals should be
zero (rather than the number of intervals supported) when an agent
first starts up.

Proposed fix (from David Fowler):  clarify that the number of invalid
intervals must be less than the number of valid intervals and that it
is intended for the proxy situation.

2.) (From Rajul Shah):  the description of sonetMediumValidIntervals
in RFC 1595 suggests that an agent is _not allowed_ to end its 15-minute
data collection intervals at 1/4 hour wall-clock boundaries, as required
by T1.231.  At issue are the words

	The value of this object will be n unless the device was
	brought online within the last (nx15) minutes, in which case
	the value will be the number of complete 15 minute intervals
	the device has been online.

Similar words appear in the descriptions of the various xyzValidIntervals
objects in all of the drafts.

Proposed fix:  clarify that if the device has come online within the
last (nx15) minutes the value of xyzValidIntervals is equal to the
number of past intervals for which the agent has collected at least
some valid data.  See also issue (3) below for how to handle an
incomplete initial interval.

[NOTE:  the trunk mib editors may wish to also consider adding some
text in the narrative part to the effect that an agent MAY choose
to align 15-minute data collection interval boundaries with 1/4
hour wall clock boundaries, but is not obliged to do so.  I believe
that this is consistent with the intent of the original RFCs, but I
could find no discussion of the issue in the atommib e-mail archives.]

3.)  (From Rajesh Abbi):  The present definition of 'xyzInvalidIntervals'
identifies an 'invalid' interval as one in which "no valid data is
available".  What about intervals in which 'some' valid data is available?

Proposed fix:  clarify that the words "valid data" in the description
of xyzValidIntervals mean "at least some valid data", and (in the
trunk mibs) clarify that the xyzIntervalValidData objects are set to
false(2) when the data the corresponding interval is incomplete (a
forthcoming memo will discuss proposals to fix the xyzIntervalValidData
description clause).

TEXT OF PROPOSED CHANGES:

In draft-ietf-atommib-perfhistTC-01.txt change

current>       -- xyzValidIntervals OBJECT-TYPE
current>       --      SYNTAX  INTEGER (0..<n>)
current>       --            -- 1 =< n =< 96
current>       --       MAX-ACCESS  read-only
current>       --       STATUS  current
current>       --       DESCRIPTION
current>       --       "The number of previous near end intervals
current>       --       for which valid data was collected.  The value
current>       --       will be <n> unless the interface was brought
current>       --       online within the last 24 hours, in which case
current>       --       the value will be the number of complete 15
current>       --       minute near end intervals since the interface
current>       --       has been online.  In the case where the agent
current>       --       is a proxy, it is possible that some intervals
current>       --       are unavailable.  In this case, this
current>       --       interval is the maximum interval number for
current>       --       which valid data is available."
current>       --       ::= { xxx }

current>       -- xyzInvalidIntervals OBJECT-TYPE
current>       --     SYNTAX  INTEGER (0..<n>)
current>       --     MAX-ACCESS  read-only
current>       --     STATUS  current
current>       --     DESCRIPTION
current>       --       "The number of intervals for which no valid
current>       --       data is available."
current>       --       ::= { xxx }

to

proposed>      -- xyzValidIntervals OBJECT-TYPE
proposed>      --       SYNTAX  INTEGER (0..<n>)
proposed>      --               1 =< n =< 96
proposed>      --       MAX-ACCESS  read-only
proposed>      --       STATUS  current
proposed>      --       DESCRIPTION
proposed>      --       "The number of previous 15-minute intervals for
proposed>      --       which at least some valid data was collected.
proposed>      --       The value will be <n> unless the interface was
proposed>      --       brought online within the last (<n>*15) minutes,
proposed>      --       in which case the value will be the number of 
proposed>      --       past intervals for which the agent has at least
proposed>      --       some valid data.  In the case where the agent
proposed>      --       is a proxy it is possible that some intervals
proposed>      --       are unavailable.  In this case, the value of
proposed>      --       this object is the maximum interval number for
proposed>      --       which at least some some valid data is available."
proposed>      --       ::= { xxx }

proposed>      -- xyzInvalidIntervals OBJECT-TYPE
proposed>      --     SYNTAX  INTEGER (0..<n>)
proposed>      --     MAX-ACCESS  read-only
proposed>      --     STATUS  current
proposed>      --     DESCRIPTION
proposed>      --       "The number of intervals in the range from
proposed>      --       1 to xyzValidIntervals for which no valid
proposed>      --       is available.  This object will typically
proposed>      --       be zero except in proxy situations."
proposed>      --       ::= { xxx }

                        =0=

In draft-ietf-atommib-sonetng-02.txt change

current>  sonetMediumValidIntervals OBJECT-TYPE
current>      SYNTAX  Integer32 (0..96)
current>      MAX-ACCESS  read-only
current>      STATUS  current
current>      DESCRIPTION
current>         "The number of previous intervals for which valid
current>         data has been stored.  A SONET interface must be
current>         capable of supporting at least n intervals.
current>         The minimum value of n is 4.
current>         The default of n is 32.
current>         The maximum value of n is 96.
current>         The value of this object will be n unless
current>         the device was brought online within the last
current>         (nx15) minutes, in which case the value will be the
current>         number of complete 15 minute intervals the device has
current>         been online. In the case where the agent
current>         is a proxy, it is possible that some intervals
current>         are unavailable.  In this case, this
current>         interval is the maximum interval number for
current>         which valid data is available."
current>      ::= { sonetMediumEntry 3 }

to

proposed> sonetMediumValidIntervals OBJECT-TYPE
proposed>     SYNTAX  Integer32 (0..96)
proposed>     MAX-ACCESS  read-only
proposed>     STATUS  current
proposed>     DESCRIPTION
proposed>        "The number of previous 15-minute intervals for
proposed>        which at least some valid data has been stored.
proposed>        A SONET interface must be capable of supporting
proposed>        at least n intervals.
proposed>        The minimum value of n is 4.
proposed>        The default of n is 32.
proposed>        The maximum value of n is 96.
proposed>        The value of this object will be n unless the
proposed>        device was brought online within the last (nx15)
proposed>        minutes, in which case the value will be the
proposed>        number of previous intervals for which the
proposed>        device has at least some data. In the case where
proposed>        the agent is a proxy, it is possible that some
proposed>        intervals are unavailable.  In this case, this
proposed>        interval is the maximum interval number for
proposed>        which at least some valid data is available."

and change

current>  sonetMediumInvalidIntervals OBJECT-TYPE
current>      SYNTAX  Integer32 (0..96)
current>      MAX-ACCESS  read-only
current>      STATUS  current
current>      DESCRIPTION
current>         "The number of intervals for which no valid
current>          data is available. This includes intervals
current>          of which valid data has been lost, e.g., due
current>          to restart of the agent."
current>      ::= { sonetMediumEntry 7 }

to

proposed> sonetMediumInvalidIntervals OBJECT-TYPE
proposed>     SYNTAX  Integer32 (0..96)
proposed>     MAX-ACCESS  read-only
proposed>     STATUS  current
proposed>     DESCRIPTION
proposed>        "The number of intervals in the range from 1
proposed>         to sonetMediumValidIntervals for which no
proposed>         valid data is available.  This object will
proposed>         typically be zero except in proxy situations."
proposed>     ::= { sonetMediumEntry 7 }

                        =0=

In draft-ietf-trunkmib-ds1-mib-08.txt change

current>  dsx1ValidIntervals OBJECT-TYPE
current>       SYNTAX  INTEGER (0..96)
current>       MAX-ACCESS  read-only
current>       STATUS  current
current>       DESCRIPTION
current>              "The number of previous near end intervals for
current>              which valid data was collected.  The value will be
current>              96 unless the interface was brought online within
current>              the last 24 hours, in which case the value will be
current>              the number of complete 15 minute near end
current>              intervals since the interface has been online.  In
current>              the case where the agent is a proxy, it is
current>              possible that some intervals are unavailable.  In
current>              this case, this interval is the maximum interval
current>              number for which valid data is available."
current>       ::= { dsx1ConfigEntry 4 }

to

proposed> dsx1ValidIntervals OBJECT-TYPE
proposed>      SYNTAX  INTEGER (0..96)
proposed>      MAX-ACCESS  read-only
proposed>      STATUS  current
proposed>      DESCRIPTION
proposed>             "The number of previous 15-minute intervals for
proposed>             which at least some valid data was collected.
proposed>             The value will be 96 unless the interface was
proposed>             brought online within the last 24 hours, in
proposed>             which case the value will be the number of past
proposed>             intervals for which the agent has at least some
proposed>             valid data.  In the case where the agent is a
proposed>             proxy, it is possible that some intervals are
proposed>             unavailable.  In this case, the value of this
proposed>             object is the maximum interval number for which
proposed>             which at least some some valid data is available."
proposed>      ::= { dsx1ConfigEntry 4 }

and change

current>  dsx1InvalidIntervals OBJECT-TYPE
current>       SYNTAX  INTEGER (0..96)
current>       MAX-ACCESS  read-only
current>       STATUS  current
current>       DESCRIPTION
current>              "The number of intervals for which no valid data
current>              is available."
current>       ::= { dsx1ConfigEntry 14 }

to

proposed> dsx1InvalidIntervals OBJECT-TYPE
proposed>      SYNTAX  INTEGER (0..96)
proposed>      MAX-ACCESS  read-only
proposed>      STATUS  current
proposed>      DESCRIPTION
proposed>            "The number of intervals in the range from 1
proposed>             to dsx1ValidIntervals for which no valid data
proposed>             is available.  This object will typically be
proposed>             zero except in proxy situations."
proposed>      ::= { dsx1ConfigEntry 14 }

                        =0=

In draft-ietf-trunkmib-ds3-mib-08.txt change

current>  dsx3ValidIntervals OBJECT-TYPE
current>       SYNTAX  INTEGER (0..96)
current>       MAX-ACCESS  read-only
current>       STATUS  current
current>       DESCRIPTION
current>              "The number of previous near end intervals for
current>              which valid data was collected.  The value will be
current>              96 unless the interface was brought online within
current>              the last 24 hours, in which case the value will be
current>              the number of complete 15 minute near end
current>              intervals since the interface has been online.  In
current>              the case where the agent is a proxy, it is
current>              possible that some intervals are unavailable.  In
current>              this case, this interval is the maximum interval
current>              number for which valid data is available."
current>       ::= { dsx3ConfigEntry 4 }

to

proposed> dsx3ValidIntervals OBJECT-TYPE
proposed>      SYNTAX  INTEGER (0..96)
proposed>      MAX-ACCESS  read-only
proposed>      STATUS  current
proposed>      DESCRIPTION
proposed>             "The number of previous 15-minute intervals for
proposed>             which at least some valid data was collected.
proposed>             The value will be 96 unless the interface was
proposed>             brought online within the last 24 hours, in
proposed>             which case the value will be the number of past
proposed>             intervals for which the agent has at least some
proposed>             valid data.  In the case where the agent is a
proposed>             proxy, it is possible that some intervals are
proposed>             unavailable.  In this case, the value of this
proposed>             object is the maximum interval number for which
proposed>             which at least some some valid data is available."
proposed>      ::= { dsx3ConfigEntry 4 }

and change

current>  dsx3InvalidIntervals OBJECT-TYPE
current>       SYNTAX  INTEGER (0..96)
current>       MAX-ACCESS  read-only
current>       STATUS  current
current>       DESCRIPTION
current>              "The number of intervals for which no valid data
current>              is available."
current>       ::= { dsx3ConfigEntry 12 }

to

proposed> dsx3InvalidIntervals OBJECT-TYPE
proposed>      SYNTAX  INTEGER (0..96)
proposed>      MAX-ACCESS  read-only
proposed>      STATUS  current
proposed>      DESCRIPTION
proposed>            "The number of intervals in the range from 1
proposed>             to dsx3ValidIntervals for which no valid data
proposed>             is available.  This object will typically be
proposed>             zero except in proxy situations."
proposed>      ::= { dsx3ConfigEntry 12 }


What say the document editors, quality reviewers, and other WG members?

Mike
--
C. M. Heard/VVNET, Inc.
[e-mail]